1. Field of the Invention
The present invention relates to a photographing apparatus and an exposure control method, and in particular, to a technique which controls an exposure at the flash photographing time.
2. Description of the Related Art
Heretofore, it has been proposed that when the flash photography is to be performed, a distance to the object is measured, and when the measured distance is equal to or greater than the distance in which the object is under-exposed by the light amount of the main emission, an amplification factor of the image signal is increased according to this distance, thereby correcting the deterioration of the image quality due to the lack of exposure (for example, Japanese Patent Application Laid-Open Nos. 6-121225, 11-41515, and 2000-134533).
Japanese Patent Application Laid-Open No. 11-84489 discloses a strobe device in which the pre-emission of a constant light amount is performed several times, and the output signals of an image pickup device obtained for each pre-emission are amplified by different amplification factor, and based on the signal whose average level is within a predetermined range among the amplified output signals, the light amount of the main emission is calculated. Further, Japanese Patent Application Laid-Open No. 11-84489 discloses a strobe device which measures the distance up to the object, and based on the measured distance, controls the light amount of the pre-emission.
Japanese Patent Application Laid-Open No. 2003-107567 discloses a photographing apparatus which controls a strobe emitting device based on the detection result of a person's face (an occupying ratio of the face inside the image plane or whether it is backlight or not). Further, the Japanese Patent Application Laid-Open No. 2005-184508 discloses a photographing apparatus in which a light modulating control area is decided according to the face area detected from within the imaging plane, and the amount of the main emission is calculated according to the photometric value at the pre-emission time in this light modulating control area.
In recent years, a high sensitivity of the photographing sensitivity of the electronic camera has been advancing. However, when the flash photography is performed with the photographing sensitivity set to high sensitivity, a phenomenon called as “over exposure” occurs, in which an object (particularly an object at a short distance) above a certain brightness level is filled dead white.
In Japanese Patent Application Laid-Open Nos. 6-121225, 11-41515, and 2000-134533, the amplification factor of the output signal is controlled by distance information up to the object, whereas, when photographing environment is so dark that the distance up to the object is unable to be measured, the distance information cannot be obtained, and a control of the adequate amplification factor is unable to be made, thereby creating a problem. Further, in Japanese Patent Application Laid-Open No. 11-84489, the light amount of the main emission is calculated based on the average level of the amplified output signals, so that, even when part of the image is overexposed, if other parts are dark, the average level of the output signal ends up falling in a predetermined range, and thus, there has been a problem that a control of the light amount of the main emission to avoid the over exposure is unable to be made. Further, Japanese Patent Application Laid-Open Nos. 2003-107567 and 2005-184508 have hardly given thought about the setting of the photographing sensitivity.